Sound recording and reproducing machine



W. E. BIRKET.

SOUND RECORDING AND REPRODUCING MACHINE. APPLiCATlON FILED MAR.- 25, 1921.

L fig o Patented July 4, 1922;

@FWCE.

WILLIAM E. IBIRKET, OF PEORIA, ILLINOIS.

SOUND RECORDING AND REPRODUCING MACHINE.

Application filed March 25, 1921.

connection with the motor thereof and the socalled tone-arm by which to govern the speed of rotation of the turn table upon Which the record-disc is carried.

In present day motor-operated machines, the turn table is rotated at a certain definite speed. That is to say, the shaft carrying said table, in one type of machine at least,

is driven at the arbitrary speed of 7 8 revolutions per minute. This shaft speed, or any other speed for that matter, means, therefore, that the record-disc must have the same speed. At the inner end or terminal of the scroll this rate of travel for the disc beneath the stylus is perhaps desirable, but at the margin of the disc the travel beneath such stylus is exceedingly rapid which means,

for purposes of comparison, that at said .margin or the starting end of the scroll a recorded sound will be very long and two recorded sounds will be very widely spaced from one another whereas at said inner terminus these recorded sounds will be short and lie very close together.

Now, were the impressions .at the margins and over the entire intervening surface of the disc as closely placed as at the said inner terminus of the scroll, it'is clear that a much longer record could be-produced in the same length of scroll for any given diameter of disc. And that this may be done, it is necessary that the rate of travel of the disc beneath the stylus be the same at all times without respect to the position of such stylus.

The main object of my invention, therefore, is that of providing mechanism for so controlling the motor, whatever its type, that the speed of travel of the disc beneath Specification of Letters Patent. 1

Patented July 4, 1922.

Serial No. 455,529.

the stylus will be the same at all positions of the latter between the beginning of the scroll and the terminus thereof, both in a recording and reproducing machine.

Another object is that of interposing mechanism between the tone-arm and the governing means for the motor, so controlled during the swing of the former that the speed of rotation of the disc will be gradually increased as the stylus moves inwardly from the start of the scroll to the inner terminus of the same, the disc, as the said terminus is reached, then rotating at the speed usually required for recording or reproducing at that point.

In order to accomplish the result stated, the rate of travel of the disc must be such, due to the constantly changing distance of travel thereof in each rotation beneath the stylus, i. e., an ever decreasing circumference, as the stylus moves toward the center of rotation, the driving mechanism, of Whatever type, must be governed in accordance.

For example, a disc twelve inches in diameter in order to have a rate of say 78 rotations per minute, must, at the outer end of the scroll, have 26 rotations when the stylus is at the start of the scroll due to the very much greater distance of travel at the point beneath the stylus in order that the recorded sounds and spacing of sounds may be the same as those at said inner end of said scroll. Now, since the stylus bears a direct relation to the scroll circumference during disc rotation, the tone-arm carrying said stylus is the controlling factor together with the power that rotates the disc. Therefore, the introduction of a suitable mechanism between the tone-arm and the power ner terminus of the scroll is approached. ,My device, however, is designed to require no change in the prevalent types of machines, being an attachment for the same.

In the accompanying drawing,

Figure 1' is a plan of a conventional type 'of sound reproducing machine,

Figure 2 is a sectional elevation of part of the same on a larger scale taken on line 2-2, Figure 1,

Figure 3 is a cross section of a tone-arm and a cam attached thereto,

Figure 4 is anelevation similar to Figure 2 in which the parts are produced on a larger scale,

Figure 5 is a plan of certain'mechanism shown in the previous figures, and t Figure 6 is a transverse section, in elevation, of a part shown both in Figure 5 and some of the other figures.

1 indicates, in this case, the cabinet of a reproducing machine, 2 the turn-table 3 the shaft or spindle carrying it, 4a record-disk, and 5 the usual tone-arm Withits sound box.

6 represents the motor for operating the turn-table, which may be of any desired type, being shown herein as a spring motor including the usual governor and friction disc 7 for controlling it. I

An adjustable part, not shown, is usually employed for governing the rate of rotation of the turn-table through a link 8 connected with a pivotally hung bell-crank 9, Figures 2 and 4, adapted to engage the friction disc 7 by a. button of felt or other material 10. Thus far I have described sound reproducing machine as usually built, with any of the forms of which my invention, now to be described, may be readily used.

11 is a lever fulcrumed at any convenient point upon or beneath the deck of the cabinet. For convenience in the present instance, it is shown pivoted beneath the turntable at 12, for example, one end having attachment to the link 8, its other end'having an arm 13 pivotally mounted thereonadapted to be adjusted withrespect to said lever by means of a screw 15 at each side of the fulcrum at 14, for example. N

16 is a thumb-screw carried by the arm adapted at times to rest upon an anvil 17 on the deck of the cabinet as will appear later.

. The arm has a downturned extension 18 at its 'free end designed to engage a cam 19 mounted upon the tone-arm to turn with the same, said extension preferably having a projection 18' to engage behind the cam for retaining the arm in operative position.

For conveniencesaid cam'is carried by a band 19' arranged to be clamped upon the said tone-arm as shown in Figure 3. It has an inclined surface 20 upon which the said downturned extension may rest and said in- .cline is of such an extent'and form that the le'verill will be moved between certainlirnits corresponding to the start and finish of the matelg record-scroll. Further, the cam preferably has an incline 21 in an opposite direction'as shown.

In order to more =readily understand the operation of the arrangement, 78 will be taken as the figure representing the usual number of revolutions of the turn-table.

Now, with the parts arranged as shown in to rise sufficiently to remove some of the .friction upon the disc 7, the motor is'permitted to speed up.

Now as the tone-arm is brought inwardly end of the lever 11 connected to the link 8 to the starting position, the incline 20 in I the swing of the tone arm having been brought beneath the extension 18, the friction upon the disc 7 is such, as adjusted by the screws 15, that the turn-table will be confined to 26 revolutions per minute for a disc having a 12 inch diameter, this speed having been found correct for that diameter of disc where speed at the innermost end of the scroll is to be 78 revolutions per minute; the cam surface 20 being so formed, with respect to the fulcrum of the lever and the manner of mounting of the parts, that the governor will be permitted to rotate faster and faster at the proper ratio.

At about one-fourth the distance of travel of the stylus inward from the starting position, the speed of the disc will be a proxi- 31 R. P. M. After the sty us has move half way across the disc, the revolutions become approximately .52 per minute, gradually increasing, until when the stylus has reached an innermost position, the speed has become 78. And if continued farther, the discJnay increase steadily at the same ameters less than 12 inches, the number of rotations when the stylus is at the margin,

must always be correct for those diameters.

It must also be evident that if the surface '20 has the same form inall cams,-

. recording and reproduction will be identical when the cams are properly set on individual machines, together with the proper'adjustment of the arms 13 with respect to the cam so as to produce the same number of revolutions of the turn-table in a given' position of the stylus.

My invention, besides admitting of much longer records being recorded and reproduced, can be so adapted without change to the reproduction of records of, the types made at the present time. p I v That'is to say, the lever 11 is so mounted at its fulcrum 12 that it may beshifted laterally suflicien'tly, as indicated in broken lines in Figure 5, that the extension 18 may be removed from the cam and dropped down whereupon the screw 16 will rest upon the anvil 17 and when properly adjusted and fixed will always be in position to so govern the motor as to admit of the required fixed speed of 78 revolutions of the disc per minute.

Such an arrangement, therefore, admits of recording and reproducing one type of record, the number of rotations constantly increasing with the travel of the stylus, which in the other case the disc may rotate for reproduction at a constant speed for a record of the common type.

The mechanism lying between the tonearm and the bell-crank 9 may be changed in position to fit any machine with such adaptations that may be necessary. Furthermore, it may be otherwise constructed to accomplish the desired result, the form shown being. but one of the types found to answer the purpose. Again, the mechanism is not confined alone to governing motors of the spring operated type, since suitable ways of afiectlng changes in the speed of other types may be readily provided.

A further advantage in overning the speed of disc rotation may be understood when it is remembered that the greater the speed beneath the stylus the more scratch is in evidence and as the stylus approaches the center of rotation, the scratching diminishes. speed, as the starting speed, with a gradual increase to properly reproduce, there will be no more of this undesirable noise at one place than another. Stated in another way, with but a minimum of noise at the finish of the scroll there will be as little at the outer margin of the disc. There are no long blank spaces. between the recorded sounds.

The screw 16 virtually corresponds to that commonly used and itsv adjustment through the lever 11 produces the same result in the control of the governor and when permanentlv set after the proper speed of rotation of the turn-table is found, the machine is always ready' to reproduce from either type of record. Said screw 16 may he placed elsewhere, of course, so long as it has control of the movement of the bell crank 9.

Clearly, modifications of the parts of the arrangement shown are possible without departing from the spirit and intent of the in vention and such as may fall within the scope of the claims, the particular, structure shown being but one of the forms that will furnish the desired results.

I claim:

1. In combination with the tone-arm and governing means of a sound recording and reproducing machine, mechanism interposed between 'the said tone-arm and governing means directly engaging both adapted in Now, by having a greatly reduced the movement of the tone-arm to control the action of said governing means.

2. In combination, with the tone-arm and motor governing means, a cam operated by said arm, and mechanism interposed between the cam and the said means, engaging both, adapted in the movement of the arm to control the said means and'the rate of rotation of the motor.

3. In combination with the tone-arm and motor governing means in a. machine for producing sound, a cam moved by the arm, and mechanism interposed between the cam and said means, engaging both, adapted in the movement of the arm to govern the speed of the motor through said means.

4. In combination with a record-disc, a tone-arm and its stylus, and power means including a governor, a part constantly changing in position in the travel of the arm with respect to the disc, of mechanism disposed between the part and the said governor to control the latter adapted therethrough to affect a constantly increasing speed rotation of the disc as the stylus moves from the outer to the inner terminus of the disc-scroll.

5. In combination with the tone-arm and governing means for the motor-of a machine of the class named, a cam moved by said arm, a lever mounted between its ends engaging at one end the cam and at its other engaging said means.

6. In a machine of the type named, a cam mounted on the pivoted end of the tonearm thereof, a lever fulcrumed between its ends engaging at oneend the governor control mechanism, and a part carried by the other end, means to adjust said part to various positions relatively to said lever and fixed in position thereon, the said part adapted to engage said cam. v

I 7. In a machine of the type named, the combination with the tone-arm and governor control means thereof, a' cam operated by the said arm, and mechanism engaging both the cam and said control means adapted to be shifted in position relatively to said cam to permit its removal therefrom.

8. In a machine of the type named, the combination with the tone-arm and governor control means thereof, a cam operated by the said arm, mechanism engaging both the cam and said control means adapted to be shifted in position relatively to said cam to permit its removal therefrom, a support for the said mechanism, and means adjustable relatively to said mechanism engaging said support.

9. "In combination with the tone-arm and governor control means in a machine of the type named, a moving part operated by the tone-arm in its movement, a'lever fulcrumed on the machine extending between the said part and said governing means having enand movable laterally on its fulcrum arranged and adapted when engaging the part to permit the turntable of the machine to rotate at a constantly increasing speed, and when removed therefrom to cause said turn table torotate at a constant speed.

10. The combination with the tone arm, motor, and motor governing means in a sound recording and reproducing machine, of a part movable with the said tone arm, and mechanism operatively connected with the said governing means and lying in the path of movement of said part adapted to be operated by the latter in its movement to cause the motor to gradually increase in its" rate of rotation, said mechanism adapted to be moved into and out of said path of said part. i

11. The combination With the tone arm,

motor, and motor governing means in a sound recording and reproducing machine,

of a part movable with said tone arm, and

by said part in the movement of the arm to cause the motor to be gradually released to gradually increase in speed of rotation,

' said mechanism'adapted to be moved out of said path of said part.

12. The combination with the tone arm, motor, and motor governing means ina ma chine of the class described, of a part movable with said tone arm, and mechanism operatively engaging the governing means and said part and mounted whereby it may be moved intoand out of the path of the part in its travel.

In testimony whereof I aflix my signature in presence of two Witnesses.

WILLIAM E. B-IR-KET.

WVitnesses:

R. J. KAVANAGH, L. M. THUnnoW. 

